The formula of nickel oxide is $\mathrm{Ni}_{0.98} \mathrm{O}_{1.00^{\circ}}$. What is the approximate…
The formula of nickel oxide is $\mathrm{Ni}_{0.98} \mathrm{O}_{1.00^{\circ}}$. What is the approximate percentage of $\mathrm{Ni}^{+2}$ in it?
92
94
96
98
Solution
Let there be 100 formula units of $\mathrm{Ni}_{0.98} \mathrm{O}_{100}$. Thus, for $100 \mathrm{O}^{2-}$ ions, there are 98 nickel ions $\left(\mathrm{Ni}^{2+}\right.$ or $\left.\mathrm{Ni}^{3+}\right)$.
Let $\mathrm{x}=$ number of $\mathrm{Ni}^{2+}$ ions.
$\Rightarrow$ Number of $\mathrm{Ni}^{3+}$ ions $=98-\mathrm{x}$.
For an electrically neutral compound:-
$\begin{aligned} & 2 x+3(98-x)+100(-2)=0 \\ & \Rightarrow x=94\end{aligned}$
So, $\%$ of $\mathrm{Ni}^{2+}=\frac{94}{98} \times 100=96 \%$